A very common method of driving elevators for office buildings, apartments and the like has been the use of a reversible DC motor powering a grooved pulley through a reduction gear train. The cables of the elevator mechanism run in tracks provided for them in the grooved pulley and are attached to the elevator car and to the counterweight at opposite ends. This type of elevator drive mechanism is particularly effective in taller buildings where hydraulic cylinder type elevators are impractical. It has the further advantage of requiring only sufficient input of energy to accelerate the elevator and counterweight mass to the desired velocity rather than bodily lifting the entire weight of the elevator as is done in a cable and windup drum mechanism.
In the common elevator drive mechanism of this type, a DC motor is connected by a drive shaft to a worm gear. The worm gear in turn drives a worm wheel which is rigidly fixed to the grooved pulley by means of a hollow cylindrical drive shaft. The entire unit is mounted for rotation about a stationary shaft with an axis coinciding with the axis of rotation of both the worm wheel and grooved pulley. The worm gear and worm wheel are commonly enclosed in a gear housing so that the gears may be adequately lubricated by a suitable lubricant. Typically this gear housing has a circular opening to permit the grooved pulley drive shaft to pass through the gear housing and connect to the grooved pulley. Because of the necessity to adjust the worm wheel to the relatively rigidly fixed worm gear, some gap, approximately 1/4 to 3/8 inch, must be provided between the outer surface of the drive shaft driving the grooved pulley and the opening provided for its passage in the gear housing.
A portion of the drive shaft interconnecting the worm wheel and grooved pulley located inside the gear housing typically had a raised rim built up around its outer circumference in a V shape. This rim cooperated with a spring loaded wiper block mounted within the gear housing to remove lubricant from the drive shaft before it progressed out of the gear housing and was lost permanently. This device proved adequate for the relatively low speed at which the elevator drive mechanism was run in the past, however, the higher speeds which have been employed in the more recent models have made this sealing means inadequate. At the speeds now used, the lubricant in the gear housing can actually be vaporized.
A need has thus arisen for a sealing means which could be placed along the drive shaft between the worm wheel and grooved pulley that would function adequately despite the necessity to alter the gap between the gear housing and drive shaft for proper adjustment of the worm wheel and yet be readily applied within the relatively cramped environment of the mechanism.